1. Field of the Invention
This invention relates to a device that efficiently transfers data to the hard disk from an external computer and thereby provides an effective computing environment (this device is referred to as “data transmission device,” or “DTS,” in this specification.
2. Description of the Related Art
The market for general-purpose computer servers is met with growing needs of late for more centralized processing at higher speeds. Conventional general-purpose computer servers perform CPU processing via an onboard local memory, and when necessary, request, store and process data from an external storage device, such as a hard disk device or silicon disk, via a system bus.
Examples of the external storage device that have traditionally been used include a hard disk device and a silicon disk using a semiconductor memory. Conventional hard disk devices have a disk head that reads data on a silicon-deposited aluminum disk, and allow for data in a given sector or block to be read when necessary.
Incidentally, the inventor had developed in the past a technology incorporating self-learning function for a direct-memory-access type server computer that uses a semiconductor memory as a data memory- to store actual data, in which the data memory recognizes as requiring fixed-area storage the addresses of data that frequently passed through during a specified sampling time, and allows such address data to reside in a fixed area of the data memory until the next sampling time is over, thereby increasing the processing speed (e.g., Laid-open Publication No. 2002-304325).
Because of their structure that incurs a seek time by the disk head, conventional hard disk devices require a very long wait time before their data can be accessed, and this has kept the overall processing speeds of computers lower. This still remains one obstacle in the improvement of overall computer performance, as it cannot be resolved simply by enhancing the CPU performance.
In other words, while conventional hard disk devices read and write data in sectors and blocks using a data-reading disk head when necessary, as explained earlier, such means is prone to lower performance when many short accesses are requested at the same time. This has resulted in poor operability of such computers.
As for conventional silicon disks that use a semiconductor memory, the available data space is limited by the capacity of the installed silicon disk, which is not enough to store an entire application. In addition, the DRAM used in these disks is a volatile data device that must be constantly supplied with power. In case of power failure, all stored data will be lost.
In an embodiment, the present invention aims to solve the above problems that have not heretofore been addressed. Specifically, it aims to significantly improve the overall performance of a computer without being limited to the performance of its hard disk and thereby solve the problem of poor retrieval performance with respect to small files, which has been an issue with conventional hard disk devices, while also resolving the problem of data loss in case of power failure as has been encountered by conventional semiconductor disks.
In other words, in an embodiment, the present invention aims to prevent the processing capability from dropping when the hard disk device is accessed from an external host computer (particularly drops in data access performance with respect to small-sized data and in random data retrieval performance), by utilizing a unique cache algorithm as well as the effect of a semiconductor memory used in a memory cache table employing the algorithm, thereby dramatically improving the retrieval capability.